.marker-cluster {
    background-color: transparent !important;
}

.marker-cluster div {
    position: relative;
    margin-left: 5px;
    margin-top: 5px;
    text-align: center;
    font-size: 16px;
    color: #fff;
    font-weight: 500;
    border-radius: 50%;
    width: 38px;
    height: 38px;
    line-height: 36px;
    background: #1f3b64;
    box-shadow: 0 0 0 4px rgba(255, 255, 255, .5);
}

.marker-cluster div:before {
    border: 17px solid #1f3b64;
    opacity: 0.5;
    content: '';
    position: absolute;
    border-radius: 100%;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    box-sizing: border-box;
    animation: cluster-animation 2.5s infinite;
}

.marker-cluster span {
    line-height: 30px;
}

@keyframes cluster-animation {
    100% {
        transform:scale(2.8) rotate(90deg);
        opacity:0;
    }
}